As a charged particle beam device, which is the measuring device, a scanning electron microscope using an electron source as a charged particle source is widely known. A scanning electron microscope emits a primary charged particle beam (primary electron beam) accelerated from an electron source, focuses the primary charged particle beam by using an electronic lens, and scans a surface of a sample with the primary charged particle beam by using an electromagnetic deflector, thereby detecting a secondary signal generated from the sample, and imaging the detected secondary signal.
In a scanning electron microscope, since a primary electron beam is focused to a small region, a fine pattern of a sample can be observed. For this reason, a scanning electron microscope is applied to a measuring device for a scanning electron semiconductor used for measuring dimension of a fine circuit pattern in a scanning electron semiconductor manufacturing process.
A measuring device for a scanning electron semiconductor used for inspecting the operation state of a scanning electron semiconductor manufacturing process repeatedly performs a series of operations for moving a sample in X and Y directions and, after the movement of the sample to the measurement position is completed, correcting a focus deviated by a height change in a Z direction, specifying a measurement point, acquiring a magnified image of the specified measurement point, and measuring the dimension of the sample.
Increasing the number of measurement points is effective for improving measurement accuracy of the measuring device for a scanning electron semiconductor. However, a high throughput is required to achieve high measurement accuracy. In embodiments of the present invention, a throughput represents an inspection speed (inspection time), such as the number of measured samples.
As methods of improving a throughput, the techniques disclosed in PTL 1 and PTL 2 is known. PTL 1 discloses a device having functions of, before performing a measurement on a sample, creating a focus map indicating positions of the sample in the Z direction (heights of a sample) for each position thereof on the XY plane and estimating a focus condition of a measurement position based on the focus map. Furthermore, PTL 2 discloses a device having a function of correcting positional fluctuation of a sample in the in-plane direction (XY direction) according to environmental changes.